For training WaveRNN, you can find discussions on the config file here:
Like erogol said, I don’t think it’s an alternate vocoder either.
Also, config files and any/all implementation of neural networks are not implicitly connected. You could possibly change everything about it depending on how you implement the pipeline.
Regardless, if you’re looking for a vocoder, Erogol’s fork of wavernn should work well with mozilla TTS’s taco2.
P.S. I might be wrong about MelNet. Reading the paper atm.